Improvement in thermostats



J'. H. GUEST.

THERMOSTATS.

No. 177,116, Patented May 9,1876.

NPEI'EEIS, PHOTO-LITNOGI RAPMER, WASHINGTON. D. C,

UNITED STATES PATENT OFEIoE.

JOHN H. GUEST, OF BROOKLYN, NEW. YORK.

IMPROVEMENT IN THERMOSTATS.

Specification forming part of Letters Patent No. l77,l16, dated May 9, 1876; application filed April 15,- 1876.

To all whom it may concern Be it known that 1, JOHN H. GUEsT, of the city of Brooklyn, county of Kings, and State of New York, have invented certain new and useful Improvements in Thermostats, of which the following is a specification In using mercurial thermostats for controlling a fire-alarm circuit much trouble has been experienced, owing to the unequal expansion of the wire entering the bulb and the glass, the glass and wire becomepartially detached, allowing air to get in the bulb, or allowing the mercury to escape by oxidation. In previous patents I show methods of preventing this by securing to the bulb a chamber, which should contain a liquid to form a liquid sea-l at thejunction of the wire and bulb.

The object of the present invention is to furnish another and even more certain means of accomplishing this; and to this end my invention consists in those features more particularly hereinafter described and claimed. Referring to the drawings, Figure l is a sectional view of my thermostat, and Fig. 2 a modification thereof. a

In both the same letters refer to the same parts as far as applicable.

7 In both these, what would otherwise be two independent thermostats are used, consisting of bulbs A A, filled with the proper quantity of mercury D D, which extends to a a, the stems beingprovided with the circuit-terminals E E.

I These otherwise independent thermostats are connected by a glass connection, 0, in which is embedded a platinum wire, B, which extends into both mercury-bulbs D D, and thus forms an electrical connection between them. It will beseen by this arrangement no air can possibly obtain access to the mercurybulbs. As the two are close together the same heat will cause the mercury to rise equally in both, and close both breaks in the circuit shown in Fig. 1 simultaneously at the designated temperature, which in this case is 100. The electrodes E E maybe fixed by having the ends of the stems fused to-them, or they may be adjustably secured therein.

In Fig. 2 the electrodes are shown as passing through a small chamber formed at the top of the stem, and partially filled with a drop or two of mercury, forming thus a reliable metallic liquid seal. It is evident that this method of sealing the connection between the mercury and wire entering the bulb may be used when only one stem is used. In such case the neck 0 is used to inclose the wire, the neck ending in a small bulb or chamber filled with mercury, as shown in Fig. 3.

. Having thus described my invention, What I claim, and desire to secure by Letters Patent, is.

1. The thermostat composed of two mercurial bulbs, stems, and electrodes, connected by an electrical connection, substantially as set forth. 7

2. In a thermostat, the stem formed with a bulb or chamber at its upper end, and provided with a liquid seal, substantially as set forth.

In testimony whereof I have hereunto atfixed my signature.

- J. H. GUEST. Witnesses:

SIMEoN SHAYO, GEORGE T. HARTSHORN. 

